Medical suction apparatus have long been used in hospitals to remove fluids from a patient during various medical procedures. One type of apparatus commonly used to receive and contain fluid from a patient includes a canister covered by a lid, with a patient port and a vacuum port communicating through the lid. A tubular vacuum line is attached between a vacuum source and the vacuum port, and another tubular line is connected to the patient port for withdrawing fluid from the patient, through the patient port and into the canister. A shutoff valve is normally used to close or block the vacuum port when the fluid within the canister rises to a predetermined level, in order to prevent the patient fluid from entering and damaging or contaminating the hospital vacuum system.
In the use of conventional canister and lid assemblies in medical suction apparatus, certain quantities of fluid droplets have been heretofore drawn through the vacuum port. For example, when fluid enters the patient port and contacts the fluid in the bottom of the canister, aerosol and splash droplets are created. These droplets tend to move through the air in straight lines, and some droplets thus find their way to the exposed vacuum port in previously developed canister lids. Also, fluid condensation droplets often form on the underside of the canister lid. Such droplets often tend to migrate along the interior surface of the lid to the vicinity of the vacuum port, where they are aspirated into the vacuum port. Prior canister and lid assemblies have not been designed to prevent or reduce such migration of aerosol, splash or condensation droplets into the vacuum port, and thus, the vacuum equipment attached to prior canister vacuum ports has been damaged or fouled. Such damage has included not only the corrosion of such parts as regulators and diaphragms, but continued deposit of such fluid droplets has resulted in the constriction of vacuum passageways, and thus, reduction of vacuum flow. Moreover, the aspiration of patient fluids into a vacuum system can cause bacteriological contamination of the vacuum system, obviously an undesirable result in a hospital environment.
A need has thus arisen for a suction canister lid assembly which eliminates or substantially reduces the aspiration of fluid droplets into the vacuum system.